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Rotating Fan Illusion

Question asked by ABCD ABCD in #Coffee Room on May 5, 2011
ABCD ABCD
ABCD ABCD · May 5, 2011
Member of CrazyEngineers
1}When you see a rotating fan, at the start it seems like rotating in opposite direction. Why does it look so? 2}This also happens when the fan is rotating at a very high speed.
In the first case, the illusion stays for few seconds. But in the second case, it remains as long as the fan is rotating. Posted in: #Coffee Room
Ammar Aziz
Ammar Aziz · May 6, 2011
Member of CrazyEngineers
really a good observation. this is due to something which i explain later inshahallah
Ramani Aswath
Ramani Aswath · May 7, 2011
Member of CrazyEngineers
mreccentric
1}When you see a rotating fan, at the start it seems like rotating in opposite direction. Why does it look so? 2}This also happens when the fan is rotating at a very high speed.
In the first case, the illusion stays for few seconds. But in the second case, it remains as long as the fan is rotating.
Stroboscopic effect. You will not see it in daylight. Tubelight, which has a high frequency flicker can cause this. Same effect is seen with car wheels or helicopter blades in films.

Bioramani
ABCD ABCD
ABCD ABCD · Jan 5, 2013
Member of CrazyEngineers
Any idea why this image looks like it is? It's a image of ceiling fan taken from a movie.
[​IMG]
No... i understood why it happens so. Thank You FOR THE ANSWERS of the prev question.
Ankush Sharma
Ankush Sharma · Jan 6, 2013
Member of CrazyEngineers
bioramani
Stroboscopic effect.

Bioramani
dear please explain some more about this effect.
Ramani Aswath
Ramani Aswath · Jan 6, 2013
Member of CrazyEngineers
Anku2993
dear please explain some more about this effect.
Here is how it works. When the frequency of the light source matches the RPM of the fan it appears stationary.

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